The present invention relates to an improvement of scissors for hair cutting or hairdressing such as cutting shears or thinning shears. In particular, the present invention relates to scissors in which, when the hair is cut or thinned, non-slip is applied so as to prevent hair from slipping at the edge of the blade of scissors in which such a non-slip effect is not degraded by sharpening of the scissors, naturally finished hair is obtained, and the improved cutting performance and abrasion resistance can be obtained.
When the hair is cut by cutting shears for hair cutting or hairdressing, as shown in FIG. 34, there occurs a phenomenon that hairs sandwiched between two blades 102, 102 slip from the heel of the blades in the point direction. Thus, the hair cutting quantity is reduced by such slip.
In addition, when a cut trace is aligned transversely in a straight line, the hair cutting is not aligned in a predetermined transverse line. As shown in FIG. 35, the cut trace is curved, which is inconvenient.
In the case where the hair is aligned in a straight line by means of the cutting shears, the straight line of the cut trace stands out too much. Therefore, this straight line is shaded, whereby natural finish is sometimes done.
However, even in the case where such linearly cut trace is shaded, straight line alignment using the cutting shears is performed as preprocessing. Then, the hair aligned in this straight line is thinned, the cut trace is shaded, and natural finish is done. Therefore, two types of scissors, cutting shears and thinning shears are used, which is cumbersome. Moreover, in such preprocessing, i.e., straight line alignment using the cutting shears, the hair is hardly aligned in a straight line. Thus, the hair must be cut many times in order to align the hair in a straight line, which is cumbersome.
In order to eliminate this inconvenience relevant to this slippage, as shown in FIG. 36,there is provided cutting shears 201 in which sectional V shaped or U shaped concave ridges 202 are continuously provided at the edge of the blade, whereby V shaped or U shaped waves are repeatedly provided to form a serrated blade shape. According to the scissors, hair is captured by concave ridges 202 of the blade, and does not slip. Thus, the problem with the above described slippage is eliminated.
The problem with hair slippage occurs with thinning shears similarly. The hair can be hardly thinned well because the hair slips while it slips at the edge of the thinning blade. In order to solve the above problem, as shown in FIG. 37 and FIG. 38, there are provided thinning shears in which V shaped or U shaped concave ridges 202 are provided at the edge of the thinning blade. According to the thinning shears, hair is captured by the concave ridges of the edge, and does not slip. Thus, the above described problem with hair slippage is eliminated.
In general, as scissors are repeatedly used, their cutting performance is degraded. Thus, the scissors are used while they are sharpened as required. Specifically, as indicated by alternate long and short dash lines in FIG. 39, a portion close to the edge of the blade is sharpened. However, sharpening such portion close to the edge of the blade shaves the concave ridges 202 formed at the edge, and. there disappear V shaped or U shaped concave ridges 202 shown in FIG. 36 to FIG. 38. In practice, the concave ridges 202 disappear, and a linear edge is obtained by performing such sharpening only one or two times. As a result, there is a problem that the hair that has not been slipped starts slipping.
In addition, in either of the cutting shears and the thinning shears as well, when the edge is formed in a V shape or U shape, the hair is captured by the concave ridges, thus forming a lock. Extra force is required when the scissors are closed to cut such locks. In addition, strong resistance is felt, and touch sense is impaired, which is not preferred in workability.
On the other hand, in general, scissors are often made of stainless having the hardness of about 650 Hv. The higher hardness improves the cutting performance more significantly. When in use, the excellent cutting performance is obtained, and strong wear and tear resistance is obtained. In general, the upper limit of the obtained hardness of stainless is about 800 Hv. As a material that exceeds this limit, there is provided a hard tool material of which the hardness of about 1000 Hv to 1500 Hv or about 2000 Hv can be obtained. However, the blade made of a material with the higher hardness becomes weaker, nicks in the edges are likely to occur. Thus, the edge angle is increased, thereby preventing such nicks in the edges. However, when the edge angle is increased in scissors, the blade hardly cuts into hair, and the hair easily slips. As a result, the slip of the, hair when the scissors are closed becomes significant, and the scissors do not function well. Therefore, scissors made of such material with the high hardness is not provided.
At present, scissors having the hardness of about 700 Hv are partially provided. This hardness is defined as the upper limit required to function as scissors in view of the presence or absence of slip. If the scissors are made of stainless having the hardness of 800 Hv, the cutting performance is improved. Further, if the scissors are made of a hard tool material with the ultra-high hardness, the cutting performance and wear and tear resistance is improved more significantly. On the other hand, there is a problem that the slip due to hair slippage becomes extremely significant, which is impractical. In particular, when the scissors are made of a hard tool material, the wear and tear resistance is expected to be about 10 times as high as conventional scissors. Although such scissors are ideal in cutting performance and wear and tear resistance, the hair slips more easily, which is impractical.
The objective of the present invention is to provide scissors in which non-slip is applied to the hair or such a non-slip state can be maintained irrespective of sharpening, a proper closing feeling is obtained, the feeling being free of strong resistance in scissors closing operation, and in particular, a required natural finished cut can be achieved in cutting shears, the scissors having excellent cutting performance and wear and tear resistance.
According to the present invention, there is provided scissors in which substantially linear slits or the like that cut out at the edge of a blade or blades are serially provided along the edge, and, by assuming a hair with predetermined thickness, a variety of slit widths of the slits are defined when the hair thickness is defined as a reference.
First, as shown in FIG. 1 to FIG. 3, a slit is defined as a slit width that is equal to or smaller than the predetermined thickness of a hair. Namely, the width of the slit is provided to be smaller than or equal to the thickness of hair. The scissors may be cutting shears or thinning shears and any other shape.
In this manner, if the slit is smaller than the thickness of a hair, as shown in FIG. 4, hair X is caught by opening 4 of slit 3, which functions as non-slip. In addition, the slit is equal to the thickness of the hair, the hair is caught similarly, which functions as non-slip. Alternatively, as shown in FIG. 5, one or two hairs X enter the slit, and are stuck in the slit. Namely, the hairs are clogged at the opening, which functions as non-slip for the hair.
Moreover, in these scissors, as indicated by alternate long and short dash lines in FIG. 6, even if the edge is sharpened and retracted, slit 3 is not eliminated as illustrated, and a non-slip effect continues to the end.
Although the above slits may be formed (manufactured) in any way, these slits can be formed as an example by grinding wheels with the thickness equal to the slit width of each of the slits. If a thin slit and a slit thicker than the slit are formed, two types of grinding wheels that correspond to these slits are provided for grinding.
If the thickness of a hair is smaller than predetermined thickness, such hair cuts into a slit. To prevent this, the slit is formed to the length that does not overreach the frictional sliding face of the scissors. In this manner, the blade is formed while the bottom of the slit crosses the frictional sliding face. Thus, the hair that has entered the slit can be cut at the bottom of the slit.
Here, the frictional sliding face S denotes a face provided at the back side of the edge. This face is provided for the reasons stated below.
In general, although a sectional shape of the blade back of the scissors has a slightly concave, curved face called back space P, as shown in FIG. 40, flat frictional sliding face S is formed only in the vicinity of the edge. This is because, when the scissors are operated to be opened or closed, a cutting action is obtained due to the sliding of frictional sliding faces S of both of the blades. The back space P is curved to be concave so as to prevent blade backs other than frictional sliding faces from coming into contact with each other. Therefore, as shown in FIG. 11 and FIG. 12, slit 5 is defined in length such that slit bottom 6 is caught by frictional sliding face S, and does not overreach frictional sliding face S. In the case where a hair with the thickness smaller than predetermined thickness enters the slit, the slit is formed in length that does not overreach frictional sliding face S of the scissors in order to provide blade 7 for cutting this hair on the bottom of blade 7. Which of the slits is formed in length that does not overreach the frictional sliding face is arbitrary. For example, in the case where large and small widths of slits coexist, slit 5 with the large width is such that a thin hair is likely to enter the slit to depths. Thus, when a blade is provided at the bottom of this slit, even if a hair cuts into the slit, such hair can be cut.
In addition, as another scissors, a slit is formed to be greater than the predetermined thickness of a hair and to be less than twice of the thickness of the hair. In order to form a blade at the bottom of the slit, the slit is formed in length that does not overreach the frictional sliding face. For example, the slit width is less than twice of the thickness of hair.
Even if the slit width is greater than the thickness of a hair, there can be achieved an effect that hairs are caught by the opening of this slit during closing operation of the scissors, and a non-slip effect is achieved. This is deemed to be because, when the scissors are closed, a number of hairs are collected at the opening of the slit, and thus, even if the opening is wider than the thickness of the hair, the densely collected hairs are caught so as to close the opening.
In addition, in these scissors, even in the case where hairs enter the slit, the width of the slit is widened. Thus, hair slip becomes proper, and no hair is clogged in the slit.
Therefore, according to these scissors, hair can be cut while non-slip is applied in the slit, and partial hairs enter the slit, and are cut therein. The hairs cut in the slit slip off from this slit, and are not clogged, thus enabling smooth closing operation and reliable straight line alignment.
As still another scissors, a predetermined width of the slit is formed such that some hairs enter a longitudinal column. The slit is formed in length that is within the frictional sliding face of the blade similarly.
According to these scissors, since the width of the slit increases; a quantity of hairs captured in the slit increases. However, since some hairs are cut in a longitudinal array, unlike conventional scissors, no strong resistance is felt, enabling smooth closing operation.
Therefore, xe2x80x9ca predetermined slit width where some hairs enter a longitudinal columnxe2x80x9d is determined as follows.
The closing resistance of scissors is caused by the length of grips of the scissors, the length of the blades, cutting characteristics of the edge. Finally, in addition to these factors, the resistance is determined depending on a quantity of hairs captured by the slit. The slit width determines a quantity of hairs to be captured in the slit (namely, the longitudinal column of hairs), whereby the resistance or smoothness when hairs are cut is determined.
Therefore, the xe2x80x9cpredetermined slit width when some hairs enter a longitudinal columnxe2x80x9d is referred to as a slit width in which, even if hairs captured in the slit are cut, there can be obtained a smooth closing resistance to an extent that a resistance is eliminated such that a lock of hairs is cut when the thinning shears are used. Thus, as long as the smoothness of closing operation is obtained, the slit width may be as wide as 0.4 mm to 0.5 mm or the like.
A xe2x80x9clongitudinalxe2x80x9d of the longitudinal column denotes a longitudinal direction of slit 3. The thickness of hair is 0.05 mm to 0.08 mm as an example. Thus, the slit of 0.2 mm to 0.25 mm in width can be exemplified. In this case, three or four hairs can enter a longitudinal column as an example.
In the case where the slit is formed in length that does not overreach the frictional sliding face, whereby the slit bottom crosses the frictional sliding face to form a blade, such crossing is formed at an acute angle (refer to FIG. 17), whereby proper cutting performance can be obtained.
If slits are ground by grinding wheels, the slit bottom is formed as a grinding trace. Thus, a way of addressing the grinding wheels relevant to the scissors may be set so that the edge angle of the slit bottom is acute.
As shown in FIG. 32, the longitudinal direction of slit 3 is defined to be substantially vertical to edge Kb of the counterpart blade at each cross point C of the scissors.
As in scissors with the slit width equal to or smaller than predetermined thickness of a hair or like scissors with the slit width exceeding and being smaller than the predetermined thickness of a hair, if a non-slip effect is intended, one end 4xe2x80x2 of the opening of the slit is at an acute angle. Thus, a catching effect increases, and a non-slip effect is improved.
In addition, when the slit width is defined in a predetermined width in which some hairs enter a longitudinal column, and is intended to cut the captured hairs by the slit, a linear blade of the counterpart blade is cut down to the hairs arranged in a longitudinal column in the slit. Thus, the improved cutting performance and the improved smoothness of closing operation can be obtained.
In any of the above described scissors as well, a xe2x80x9cportion at which the slits are serially providedxe2x80x9d may be arbitrarily disposed along the edge. Namely, the slits may be serially provided over the full length of the blade or may be serially provided partly of the full length of the overall blade. For example, the slits may be serially provided at only a portion close to the point of the blade, and a general linear blade may be formed at the other portion. Alternatively, the slits may be serially provided at only a portion close to the heel of the blade or may be serially provided at any portion. In addition, the serially provided portion may be roughly or finely provided at the slit.
Depending on the presence or absence of such serially provided portion, the edge of the scissors is divided into a portion at which hair is cut without slippage and a portion at which hair is cut with slippage, corresponding to the presence or absence of the serially provided portion. The presence or absence of such slippage is brought onto the edge line. Thus, the hair cut trace is not linear, waves corresponding to disposition of the xe2x80x9cserially provided portionxe2x80x9d are irregular, and natural change in finish is obtained.
In addition, at the serially provided portion, the large and small gaps of the slits can be differentiated with such each portion, an extent of the xe2x80x9cnon-slipxe2x80x9d depends on this difference. Thus, the hair cut trace becomes irregular as in waves corresponding to the large and small gaps, as shown in FIG. 21. In addition, with respect to one serially provided portion as well, equal pitches are provided at that portion or the large and small gaps may be provided with unequal intervals.
Likewise, arbitrary disposition of the xe2x80x9cportion at which slits are serially providedxe2x80x9d at the edge and the large and small gaps of the slit at the serially provided portion are used altogether, whereby various finishes of hairs can be obtained. Alternatively, there may be provided scissors in which either one of arbitrary disposition and the large and small gaps of the slit are achieved without using them.
In any of the above described scissors, shallowly cutout, substantially concave engagingly fit slits may be serially provided instead of the slits (FIG. 33). This engagingly fit slits denote a slit providing engagingly fit to an extent that hairs serve as non-slip at a concave ridge that is more recessed than the edge rather than a slit formed in a shape in which-hairs enter a slit.
In addition, as described in the Background of the Invention section, hair slip significantly when a material of the scissors has the predetermined hardness or more. Thus, such material with high hardness has not been used. However, according to the present invention, a non-slip effect is achieved, and such material with high hardness can be used as a material of the scissors. As a result, the improved cutting performance, wear and tear resistance, and the non-slip effect can be achieved by a pair of scissors, and a very excellent pair of scissors can be obtained.
In particular, the aforementioned effect becomes more significant by using a hard tool material for the scissors.
Specific examples of material include: stainless of about 800 Hv in hardness or high-speed tool steel and the like. Examples of hard tool materials include powder metallurgy high-speed tool steel, ultra-fine particles, cemented carbide, cermet, sintered ceramics, cubic boron nitride (CBN) or the like.
The scissors assume that two blades are made of materials with the hardness identical to each other. In order to maintain the scissors cutting performance, a magnitude difference in hardness of the blade material is provided between these two blades opposite to each other, and slits may be provided at only the blade with the high hardness.
The reason is stated as follows. In general, the scissors in use is subjected to hair grease at the edges. When the slide faces of the two blades with the differential hardness are covered with grease film, this grease serves as sharpening lubricant on the frictional sliding faces. When the scissors are operated to be opened and closed, there can be achieved an effect that the frictional sliding face on the high hardness side sharpens the frictional sliding face on the low hardness side. Thus, the scissors is sharpened at the same as when in use, and therefore, the blade on the low hardness side can maintain a state in which its edge is always sharpened. In addition, the blade on the high hardness side originally has a wear and tear resistance, and the siding counterpart is a blade with the low hardness. Therefore, the blade on the high hardness side is less worn. Shortly, there is provided scissors in which both of the blades are always kept sharpened, and a proper cutting performance is maintained.
For example, there is a method in which one blade is made of ceramics, slits are formed on the blade, and the other blade is made of stainless (for example, 650 Hv in hardness). Alternatively, the blades may be made of cermet or stainless and any other material combination. If the wear and tear velocity of the blade on the low hardness side is high, the magnitude difference in hardness between the blades is reduced. Conversely, if the wear and tear is low, and there cannot be achieved a sharpening effect on the blade on the low hardness side, materials may be selected in order to expand the magnitude difference in hardness.